Machine for setting heat-shrinkable sleeves on objects from a continuous sheath

ABSTRACT

The invention relates to a machine for fitting sleeves of heat-shrink plastics material on objects, the sleeves being taken from a continuous sheath that is rolled flat. In the invention, a horizontal shaping mandrel ( 40 ) is provided that comprises two torpedoes ( 41, 42 ) in axial alignment and interconnected by a thread-like central element ( 43 ), the two torpedoes having facing ends ( 45, 46 ) each with a pair of smooth chamfers, and each torpedo resting freely on an associated V support ( 60 ). The sheath drive means comprises two adjacent pinch wheels ( 25, 26 ) disposed symmetrically on either side of the thread-like element ( 43 ) between the two V-supports ( 60 ) and passing in the vicinity of the pairs of smooth chamfers of the torpedoes ( 41, 42 ), each wheel ( 25, 26 ) having a peripheral groove ( 65, 66 ) that is complementary to the groove of the other wheel so as to form a horizontal axis passage for said thread-like element.

FIELD OF THE INVENTION

The present invention relates to a machine for fitting heat-shrinkplastics material sleeves on objects, in particular elongate objects ofsmall section, the sleeves being taken from a continuous sheath that isrolled up flat.

BACKGROUND OF THE INVENTION

In a technique that is conventionally used in this field, this type ofmachine for fitting sleeves has a shaping mandrel over which the sheathis passed in order to open it, sheath drive means using motor-drivenwheels which co-operate with an associated portion of the shapingmandrel to fit the open end of the sheath on an object, and cutter meansthat act between the shaping mandrel and the object to form a sleevethat is associated with said object.

Thus, over the last score or so years, a concept has been developed ofshaping mandrels that are mounted floating and that extend vertically.On this topic, reference can be made to the following documents: FR-A-2490 590, U.S. Pat. Nos. 3,792,807, 3,910,013, 4,016,704, 4,600,371,GB-A-1 430 090, and EP-A-0 109 105.

To transfer the sheath continuously around the shaping mandrel, themachines described in the above-specified documents use motor-drivenpresser wheels co-operating with backing wheels carried by the shapingmandrel, with the sheath that surrounds the shaping mandrel whiletraveling along it being clamped between the motor-driven presser wheelsand the backing wheels which are mounted idle on axles associated withthe mandrel. Those techniques are now thoroughly understood and inwidespread use for fitting sleeves on objects such as flasks, bottles,and other containers.

Nevertheless, if it is desired to use sheaths of small diameter forputting on objects that are fine and elongate, i.e. sheaths of adiameter considerably smaller than 20 mm, the above technique usingbacking wheels mounted idle on the shaping mandrel becomes impractical.It is not possible to envisage mounting backing wheels on a shapingmandrel of diameter significantly smaller than 20 mm since such backingwheels would then be very small in diameter which would require them torotate at very high speeds of rotation as the sheath travels along theshaping mandrel, and that would give rise to phenomena of wear andoverheating that are incompatible with reasonable use on an industrialscale.

Proposals have also been made to organize the travel of the sheath overa shaping mandrel by pinching the sheath between two motor-driven wheelsat an intermediate opening in the shaping mandrel.

Thus, document JP-A-1 410 808 discloses a floating mandrel type shaperhaving, in addition to an arrangement of wheels and idle backing wheels,a central window in which two motor-driven wheels pinch the walls of thesheath. However, the floating mandrel continues to be supported by thewheels and the backing wheels provided further up the shaper. Using thesame approach, document U.S. Pat. No. 2,765,607 illustrates a floatingmandrel which is constituted by two portions interconnected by siderods, with a central gap being formed in which the motor-driven driverollers pinch the walls of the sheath. The floating mandrel is thensupported by a rounded surface of the flattened top portion (which alsoforms an insertion spatula) bearing against the two motor-drivenrollers. The bottom portion having a circular base then serves as ashaper and as a counterweight. Reference can also be made to documentFR-A-2 738 797 which shows a shaper having two torpedoes interconnectedby a plate where the sheath is pressed by driven wheels, or indeed todocument EP-A-0 368 663 which shows a shaper having two floatingmandrels, one of which is flat with a window (through which the sheathis pinched by drive wheels), while the other is torpedo-shaped, anddisposed downstream from the cutter device.

In a variant, as shown in document FR-A-2 061 240, proposals have alsobeen made to use a vertical shaper made up of two torpedoesinterconnected by a rod, with drive wheels that pinch the flattenedsheath in the vicinity of the rod, and with contact via four idle wheelsbeing provided on each of the torpedoes. In that case also, the use ofbearing wheels prevents the use of sheaths of small diameter.

Finally, the shaping mandrels shown in the above-mentioned documents donot really serve to solve the problem of transferring sheaths of verysmall diameter since inevitable phenomena of overheating and wear arise,which phenomena run the risk of damaging or even tearing the continuoussheath while it is being transferred over the mandrel. This isparticularly true when it is desired to use such a machine at high ratesof throughput, e.g. one hundred to two hundred sleeves fitted perminute. A sheath of diameter lying in the range 5 mm to 20 mm gives riseto a flat ribbon of narrow width (8 mm to 31 mm), and the flat ribbon isthen relatively rigid and difficult to pull. The high mechanicalstrength gives rise to high forces that need to be overcome, from whichthe above-mentioned phenomena of overheating and wear arise. Inaddition, when rates of throughput are high, the positions of objectstraveling beneath the shaper need to be controlled by using clamps orthe like, thereby further complicating the structure of the fittingmachine.

In general, the above-described techniques do not genuinely make itpossible to optimize expanding the sheath while accurately controllingthe section of the sheath as it leaves the shaping mandrel to engage onthe object concerned. This makes it necessary to provide sheaths ofdiameter that is considerably greater than that of the objects they areto cover. Consequently, it is not possible to control the position ofthe sleeve in satisfactory manner, either axially or transversely. Thisbecomes particularly critical when the sleeve is to be shrunk onto theobject, in so far as the sleeve can be poorly positioned on the objectand in any event shrinking needs to be that much greater. The personskilled in the art is well aware of the difficulties encountered undersuch circumstances, and in particular concerning attempts to control theposition and the shrinking of the sleeve, above all when such a sleevehas printed wording and/or decoration thereon.

SUMMARY OF THE INVENTION

The invention seeks specifically to resolve that problem by designing asleeve-fitting machine that gives higher performance while avoiding theabove-mentioned drawbacks.

Thus, the object of the invention is to design a machine for fittingsleeves of heat-shrink plastics material on objects starting from acontinuous sheath that is rolled up flat, the machine being entirelycompatible with sheaths of small diameter, e.g. diameters lying in therange 5 mm to 20 mm, while nevertheless being capable of operating athigh rates of throughput, i.e. considerably exceeding 200 sleeves fittedper minute, with the positions of the sleeves as fitted on the objectsnevertheless being properly controlled.

According to the invention, this problem is resolved by a machine forfitting sleeves of heat-shrink plastics material on objects, the sleevesbeing taken from a continuous sheath that is rolled up flat, the machineincluding a shaping mandrel over which the sheath passes in order to beexpanded, sheath drive means using motor-driven wheels which co-operatewith an associated portion of the shaping mandrel to engage the open endof the sheath on an object, and cutter means intervening between theshaping mandrel and the object so as to form a sleeve associated withsaid object, the shaping mandrel being substantially horizontal andcomprising two torpedoes in axial alignment interconnected by athread-like central element, with an upstream torpedo having an upstreamend forming an insertion spatula and a downstream end with a pair ofsmooth chamfers, and a downstream torpedo presenting an upstream endwith a pair of smooth chamfers and a downstream end with a straight edgeadjacent to the cutter means, each torpedo of said mandrel restingfreely in an associated V-support, and the sheath drive meanscomprising, between the two V-supports, two adjacent pinch wheelsdisposed symmetrically on either side of the thread-like element of theshaping mandrel and passing in the vicinity of the chamfered smoothedges of the torpedoes, each wheel having a peripheral groovecomplementary to that of the other wheel so as to form a horizontal axispassage for said thread-like element.

By means of such an arrangement of two horizontal torpedoesinterconnected by a thread-like central element, with the smoothdouble-chamfer ends thereof being free from bearing wheels, it ispossible to organize the opening and rapid transfer of continuoussheaths of very small diameter. In addition, horizontal transfer makesit considerably easier to control the positions of the objects, even athigh rates of throughput, e.g. by using sprocket-wheels.

It should be observed that the floating mandrel techniques described inthe above-cited documents would be completely impractical fortransferring a sheath horizontally.

Preferably, the insertion spatula of the upstream torpedo extends in aplane which is substantially perpendicular to the plane in which thecontinuous sheath is pinched between the two wheels. This makes itpossible to shape the sheath around the mandrel which confers anace-of-diamonds shape to the section of said sheath on leaving a shapingmandrel whose downstream torpedo is of substantially circular section,said shape being favorable both for transferring the sheath gently ontoa cylindrical object, and for ensuring that the sheath is cut cleanlyand without creasing downstream from the shaping mandrel. Naturally, itis possible to provide special shapes for the outlet section of thedownstream torpedo in order to preform the sheath in ways that areadapted to the section of the object concerned.

Advantageously, the upstream torpedo and/or the downstream torpedo hastwo plane side facets substantially perpendicular to the plane in whichthe continuous sheath is pinched between the two wheels. These planeside facets decrease the side friction between the sheath and thetorpedoes of the shaping mandrel, which is particularly favorable whensaid sheath carries a deposit of varnish or of some other material onits inside wall.

Preferably, the thread-like element is a flexible wire anchored at bothends in the torpedoes, one of the anchored ends being releasable so asto enable the length of said thread-like element between said torpedoesto be adjusted. For example, the thread-like element can be constitutedby a steel wire having a diameter of about 1 mm.

Also preferably, the pairs of smooth chamfers of the upstream anddownstream torpedoes are formed by sloping plane facets disposedsymmetrically about a midplane containing the thread-like element andtangential to the two pinch wheels.

In particular, the pair of smooth chamfers of the upstream torpedo isformed by two plane facets sloping at about 30°, and the two pinchwheels pass tangentially over said pair of smooth chamfers, while thepair of smooth chamfers of the downstream torpedo is formed by two planefacets that slope at a smaller angle. It is also possible to provide forthe pair of smooth chamfers to be defined by two fitted inserts, thatare preferably interchangeable, having free facets constituting thesloping plane facets that co-operate with the pinch wheels.

A longitudinal slot can also be provided at the bottom of the V-grooveof each torpedo support: such a slot makes it easier to pass the bottomfold of the sheath and avoids crumpling it.

According to another advantageous characteristic, the cutter meanscomprise a blade carried by a rotary arm on a horizontal axis, and saidmeans is positioned in such a manner that its blade is flush with thestraight edge of the downstream end of the downstream torpedo.

It is then preferable for the cutter blade to have two rectilinearcutting edges that meet at a leading edge and for the two cutting edgesto be substantially perpendicular and arranged in such a manner that theleading edge meets the top of the sheath in the vicinity of a creasetherein that results from said sheath passing over the insertion spatulaor between the two pinch wheels.

The cutter means organized in this way makes it possible to obtain aperfectly clean cut that is made progressively, without folding thesheath, and in a very short length of time.

According to another advantageous characteristic of the invention, thetwo pinch wheels are peripherally coated in elastomer, and come intocontact with each other on either side of their peripheral grooves whichare trapezoidally shaped and present two facets sloping symmetricallyabout their midplane, forming a V that opens at an angle of about 60°,and the two pinch wheels are chamfered on their outer edges.

Advantageously, the two pinch wheels are mounted on a carrying structurecapable of pivoting, preferably about a vertical axis, so as to enablethe drive means as a whole to be offset laterally. It then becomes easyto take action quickly for cleaning or for the purpose of changingsheath format.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will appear moreclearly in the light of the following description and the accompanyingdrawings, relating to a particular embodiment, and with reference to thefigures, in which:

FIGS. 1 and 2 are a front view and a side view of a machine of theinvention for fitting sleeves, said machine also being provided with ashrinking tunnel so as to constitute a unitary machine;

FIG. 3 is an elevation view in greater detail showing the horizontalshaping mandrel made of up two torpedoes and two adjacent pinch wheelsdisposed on either side of the thread-like element interconnecting thetwo torpedoes;

FIG. 4 is a plan view of the assembly shown in FIG. 3;

FIG. 5 is an elevation view (partially in section) on a larger scale ofthe horizontal shaping mandrel, and FIG. 6 is a plan view thereof;

FIG. 7 is a section view on VII—VII of FIG. 3, and FIG. 8 is afragmentary view on a larger scale showing the horizontal shapingmandrel over which the sheath passes;

FIG. 9 is a section view on IX—IX of FIG. 3, and FIG. 10 is afragmentary view on a larger scale showing more clearly thehorizontal-axis passage defined between the two adjacent pinch wheels;

FIG. 11 is a section on XI—XI of FIG. 3, and FIG. 12 is a detail sectionon a larger scale analogous to that of FIG. 8;

FIG. 13 is a detail view showing how the advance of the sheath over anobject is stopped immediately before the sheath is cut;

FIG. 14 is a detail view showing an object in a slot of a dualsprocket-wheel, fitted with a segment of sheath whose section isace-of-diamonds shaped;

FIG. 15 is a detail view showing a preferred embodiment of the means forcutting the sheath; and

FIG. 16 is a detail view showing a variant in which the downstream endof the upstream torpedo has a smooth double chamfer defined by twoinserts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a machine 1 for fitting sleeves of heat-shrinkplastics material on objects, the material being taken from a continuoussheath that is rolled flat, and the machine being organized inaccordance with the invention.

The machine comprises a main stand 2 carrying a glazed compartment 3 inwhich there are located all of the mechanical members for feedingobjects, and also for horizontally transferring a continuous sheath thatis rolled up flat, with the sheath being advanced progressively so as towrap each individual object, and with the sheath being cut so as to formsheath segments or “sleeves”. A control unit 4 supported on a pivotingbracket 5 enables the operator to monitor the various parameters of thesleeve-fitting machine, and optionally to modify certain adjustments ofthe operating cycle.

The elongate objects 10, e.g. pens for drawing, arrive via a feed hopper6 which delivers them to a dual sprocket-wheel 7 rotated by a motor 8,the dual sprocket-wheel having peripheral slots 9 suitable forsupporting each elongate object 10 at two locations. An object receivedin two aligned slots 9 of the dual sprocket-wheel 7 then progressesbecause the dual sprocket-wheel is rotating, until it reaches a station11 for monitoring that an object is indeed present (with this functionbeing performed by means of an optical sensor, for example), after whichit reaches a station 12 which is the fundamental station for advancingthe sheath and cutting off a length thereof so as to define a segment ofsheath or sleeve that covers the object 10. The object 10 covered in itssleeve then continues its circular path until it reaches a bottom guide13 which prevents it from falling away, after which it is delivered toan outlet chute 14, organized immediately below the axis of the dualsprocket-wheel 7 in this case, with the sleeved object then droppingonto a conveyor 16 which travels horizontally as represented by arrow200. Any objects found to be defective, i.e. having a poorly positionedsleeve, are expelled via an evacuation chute 15. The objects 10 insidetheir sleeves as deposited onto the conveyor 16 then pass individuallythrough a shrinking tunnel 17 fitted with heater elements (not shown),e.g. infrared heater elements, for the purpose of shrinking each sleeveon the associated object. On leaving the machine, the objects coated intheir shrunk sleeves are recovered in a hopper 18.

FIG. 2 shows more clearly a continuous sheath 20 rolled up flat to forma supply reel 21 mounted on a fixed support 22, with the sheath beingdelivered from the reel by passing over various rollers until it comeslevel with a station 12 for transferring the sheath horizontally. Thesheath is driven by sheath drive means 90 having two motor-driven wheels25 and 26, themselves driven via a belt 27 passing over the outlet shaftof a drive motor 28. As explained below, the sheath is then clampedbetween the two wheels 25 and 26 between two torpedoes that constitutethe horizontal shaping mandrel. The sheath reaches the transfer station12 after passing between two guide rollers 29, in this case havingvertical axes, while the sheath is still in its flat position, with thesection of the sheath then extending in a plane that is substantiallyvertical. Cutter means 30, described in greater detail below, areorganized at the outlet from the transfer station 12, in the vicinity ofthe dual sprocket-wheel 7 so as to cut off the end of the sheath that isengaged on an object, thereby defining a sheath segment or “sleeve”.

In this case, the sheath drive means 90 and its two motor-driven wheels25 and 26 are mounted on a load-carrying structure 23 organized in theform of a turret secured to a fixed cross-member 24, and capable ofpivoting about a vertical axis 19. Such a pivoting configuration enablesthe drive means 90 as a whole to be offset laterally. This is mostadvantageous in practice since it enables an operator to take actionquickly and easily via the access thus released to the components of thedrive means in order to perform a cleaning or maintenance operation, orindeed in order to change the format of the sheath. Once the operationhas been performed, the operator returns the moving equipment to itsoperating position and the assembly returns directly to its positionwhere it is in alignment with the object. In addition to making itpossible for intervention to take place quickly, this pivoting mountenables the drive means of the fitting machine to be implemented inhighly compact form.

There follows a description in greater detail of the organization of thehorizontal shaping mandrel and the two associated pinch wheels,described with reference to FIGS. 3 to 12.

As in the prior art, the fitting machine has a shaping mandrel overwhich the sheath is passed in order to expand it, drive means fordriving the sheath by means of motor-driven wheels which co-operate withan associated portion of the shaping mandrel in order to engage the openend of the sheath on an object, and cutter means that act between theshaping mandrel and the object-supporting sprocket-wheels in order toform a sleeve associated with said object.

Nevertheless, the shaping mandrel 40 of the fitting machine of theinvention is organized in a manner that is very particular, as describedbelow. The shaping mandrel 40 is substantially horizontal (withreference to its axis 100) and it comprises two torpedoes 41 and 42 inaxial alignment and interconnected by a thread-like central element 43.Thus, there is an upstream torpedo 41 having an upstream end 44 thatforms an insertion spatula and a downstream end 45 having a pair ofsmooth chamfers (i.e. it has no bearing wheels), and a downstreamtorpedo 42 having an upstream end 46 with a pair of smooth chamfers(i.e. it has no bearing wheels), and a downstream end 47 having astraight edge 51 adjacent to the cutter means 30. The terms “upstream”and “downstream” are used herein relative to the travel direction of thesheath, which is represented in FIGS. 3 and 4 by an arrow 101.

The thread-like element 43 may be constituted by a flexible steel wirehaving a diameter of about 1 mm, for example, and it has its two ends 52and 53 secured in the two torpedoes 41 and 42, respectively. The end 52has an end toggle which enables it to be held in abutment by naturalwedging, while the end 53 is fixed via releasable anchor means. One suchreleasable anchor system can be seen in particular in FIG. 5 which makesuse of a clamping jaw 54 having a conical outside surface bearingagainst an abutment cone 55, together with a clamping bushing 56 engagedin an associated open tapped end 57 of the downstream torpedo 42.Tightening the bushing 56 into the associated thread 57 serves to urgethe clamping jaw 54 against the abutment cone 55, thereby securing theend 53 of the thread-like element 43. By releasing the bushing 56, it ispossible to slide the steel wire through the anchor elements and thus toadjust the position of the wire relative to the downstream torpedo 42.This adjustment option is advantageous in practice since it enables thelength of the thread-like element 43 between the horizontal torpedoes 41and 42 to be adjusted. This adjustment is important insofar as the pinchwheels 25 and 26 are received accurately between the facing ends of thetorpedoes 41 and 42 while passing over the thread-like element 43.

The downstream end 45 of the upstream torpedo 41 and the upstream end 46of the downstream torpedo 42 are shaped so as to have respective pairsof smooth chamfers. These pairs of chamfers referenced 48 and 49 for theupstream and downstream torpedoes 41 and 42 are constituted by slopingplane facets arranged symmetrically about a midplane containing thethread-like element 43, and tangentially to the wheels 25 and 26. As canbe seen more clearly in FIG. 5, the pairs of smooth chamfers 48 of theupstream torpedo comprise two sloping plane facets, e.g. sloping at anangle of about 30°, and the two pinch wheels 25 and 26 pass tangentiallyover said pairs of smooth chamfers. Given the large amounts of frictionthat exist at the pair of smooth chamfers 48 of the upstream torpedo 41,provision can be made for said pair of chamfers 48 to be defined byfitted inserts. The detail of FIG. 16 shows such a variant and shows theend 45 of the upstream torpedo 41 fitted with small plates 75 which arepreferably interchangeable, having free faces that constitute thesloping plane facets that co-operate with the pinch wheels 25 and 26.These small plates 75 can be made of any suitable material, for examplea plastics material or a ceramic. Surface state at the pairs of smoothchamfers 48 is thus fully under control. The pair of smooth chamfers 49of the downstream torpedo is formed by two facets that slope at ashallower angle.

In order to transfer the sheath horizontally (the shaping mandrel alwaysremains substantially horizontal), each torpedo 41, 42 of the shapingmandrel 40 rests freely on an associated V-support 60, with the twodrive wheels 25 and 26 being arranged between the two V-supports. Thesection of FIG. 7 and the detail of FIG. 8 show one of these supports 60more clearly, together with its V-shaped facets referenced 60.1 thatserve to ensure that the torpedoes are properly centered on their axis.In this case, the supports 60 are associated with a top abutment 61 thatprevents the torpedo 41 from being raised. It will also be observed thatthere is a longitudinal slot 60.2 in the bottom of the V-groove of eachsupport 60. This slot makes it easier to pass the bottom crease of thesheath along the bottom of the groove, and considerably reducesfriction, thereby making it easier to pull the sheath along withoutrunning any risk of crumpling it.

FIGS. 7 and 8 also show the presence of two plane side facets 58 on thetorpedo 41, which facets are substantially perpendicular to the plane inwhich the continuous sheath is pinched between the two wheels 25 and 26.These plane side facets 58 make it possible to avoid excessive pressurefrom the sides of the sheath, and this is particularly advantageous whenthe sheath is coated on its inside face in a special varnish or thelike.

On passing over the insertion spatula 44, the sheath 20 is flat, howeverit is expanded progressively as it passes onto the main portion of theupstream torpedo 41 whose section is substantially circular. Althoughnot shown in FIGS. 7 and 8, the sheath will in practice present a smallcrease along the top and the bottom of the sheath as a result of itsinitial flat shape.

As can be seen more clearly in FIGS. 9 and 10, the two adjacent pinchwheels 25 and 26 are disposed symmetrically on either side of thethread-like element 43 of the horizontal shaping mandrel 40, and eachwheel 25, 26 has a peripheral groove 65, 66 that is complementary tothat of the other wheel 26, 25 so as to form a horizontal-axis passage67 for said thread-like element. As can be seen in FIG. 3, the adjacentpinch wheels 25 and 26 also pass close to the smooth chamfers of thetorpedoes 41 and 42, i.e. the sloping plane facets 48 of the upstreamtorpedo 41 and 49 of the downstream torpedo 42. The sheath 20 passingover the upstream torpedo 41 and reaching the pair of smooth chamfers 48is then pinched by the two rollers 25, 26 which flatten the sheath ontothe thread-like element 43 while also transferring it horizontally, andthe sheath is not jammed in any way on said thread-like element, becauseof the presence of the peripheral grooves 65 and 66 which define thepassage 67. In FIG. 9, there can also be seen the housings 62 and 63that carry the wheels 25 and 26, and at the other ends of said housings,the pulleys 64 over which the above-mentioned transmission belt 27passes to drive rotation of the wheels 25 and 26.

The arrangement of the wheels 25 and 26 is shown in greater detail inFIG. 10.

In this figure, it can be seen that the wheels 25 and 26 are in contactwith each other on either side of their peripheral grooves 65 and 66. Inpractice, the peripheries of these two pinch wheels 25 and 26 are coatedin an elastomer, e.g. a polyurethane of suitable hardness. Theperipheral groove 65, 66 of at least one of the two pinch wheels 25, 26(and in particular the grooves of both of them) can be of trapezoidalshape as shown in FIG. 10 (naturally in a variant a different shapecould be provided, in particular a conventional V-shape). The twogrooves 65 and 66 then have two sloping facets 68 and 69 inclinedsymmetrically about the midplane of the two wheels 25, 26, referenced P,thereby forming a V-shape opening at an angle of about 60°. These facets68 and 69 contribute to overall guidance and prevent the travelingsheath being offset sideways as it passes over the thread-like element43. It should also be observed that chamfers 70 and 71 are present onthe outside edges of the wheels 25 and 26. These chamfers 70 and 71avoid excessive compression being applied to the sheath 20 since thatwould create a crease in the vicinity of the edges of said sheath andthe resulting marking would be difficult to eliminate during shrinkageof the sleeve on the object. The thread-like element 43 remains inposition in the midplane P because the upstream and downstream torpedoes41 and 42 that form the horizontal shaping mandrel 40 are bothpositioned correctly.

Downstream from the pair of wheels 25, 26, the sheath 20 passes over thedownstream torpedo 42, and the free edge of said sheath comes level withthe free edge 51 of said torpedo, and in this case said edge forms aright circle. FIGS. 11 and 12 show the plane side facets 59 that arealso provided on the downstream torpedo 42 to avoid excessive friction,in the same manner as the facets 58 on the upstream torpedo 41. Althoughnot visible in FIG. 12, the sheath which passes horizontally between thesupports 60 and 61 and the downstream torpedo 42 does in fact have asmall amount of creasing along four edges so as to give it a section inthe form of an ace-of-diamonds. The top and bottom creases correspond tothe sheath passing over the insertion spatula 44, while the two sidecreases correspond to the sheath passing between the two adjacent pinchwheels 25 and 26.

It is advantageous for the sheath 20 to have a section with anace-of-diamonds shape insofar as the resulting quadrilateral fits neatlyon the section of the object 10 that is to be covered and can slidelightly along said object. This is favorable for obtaining very accurateaxial and transverse positioning of the sleeve on the object. Inaddition, when the object fitted with its sleeve comes into theshrinking tunnel, shrinkage is limited, insofar as the sheath istangential to the object to be covered in four different side zones, soshrinkage takes place mainly at the four lightly-marked creases.

The circular shape of the outlet section of the downstream torpedo 42 ismerely an example, and other special shapes could be provided (e.g.square, lozenge-shaped, or elliptical) as a function of the shape of thecorresponding object, so as to preform the sheath that leaves theshaping means in a manner that is entirely suited to the section of theobject. This facilitates accurate positioning and makes high rates ofthroughput possible when fitting sleeves, which rates can exceed 200sleeves fitted per minute.

In FIG. 3, there can also be seen cutter means 30 constituted by a blade31 mounted on an arm 32 that rotates about a horizontal axis 32′, underdrive from an associated motor 33. In practice, the plane referenced 50in which the rotary blade 31 moves is immediately adjacent to thestraight edge 51 of the downstream torpedo 42, thereby contributing tocutting the sheath accurately and without creasing during the cuttingstage. Naturally, it is also possible to provide guillotine-type cuttermeans, but tests performed by the Applicant have shown that a rotaryblade gives excellent results in obtaining a cut that is entirely clean,and in addition provides the option of a special arrangement that isdescribed below in greater detail with reference to FIG. 15.

As can be seen in FIG. 13, the continuous sheath 20 passes beyond thestraight edge 51 of the downstream torpedo 52 so as to engage on anobject 10 that is to be covered, with this taking place over a lengththat is predetermined in advance (and may be as long as the full lengthof the object). Once this advance has been reached, the drive to themotor-driven wheels 25 and 26 is stopped and cutting takes place in thecutting plane 50. The detail of FIG. 14 shows clearly the element 10received in a slot 9 of the dual sprocket-wheel 7, and covered in thesheath 20 with an ace-of-diamonds shaped section. Once cutting has takenplace, the segment of sheath removed in this way forms a sleeve 80 whichis subsequently to be shrunk onto the object 10 in the shrinking tunnel17 of the fitting machine.

A preferred embodiment is described below for the cutter means 30 withreference to FIG. 15.

In FIG. 15, there can be seen the cutter means 30 having a blade 31carried by a rotary arm 32 on a horizontal axis 32′ parallel to the axisof the torpedoes 41 and 42, said means preferably being positioned insuch a manner that its blade 31 is flush with the straight edge 51 ofthe downstream end 47 of the downstream torpedo 42, as described above.Specifically, the cutter blade 31 has two rectilinear cutting edgesreferenced 31.1 and 31.2 which meet at a leading edge referenced 31.3.The two cutting edges 31.1 and 31.2 are preferably substantiallyperpendicular to each other and are arranged so that the leading edge31.3 makes contact with a top edge of the sheath 20 in the vicinity of acrease line thereof that results from said sheath passing over theinsertion spatula 44 or between the two pinch wheels 25 and 26.Specifically, there is shown an arrangement in which the two cuttingedges 31.1 and 31.2 meet a top crease 20′ of the sheath 20, however itwould be entirely possible for the engagement to take place at someother crease. This arrangement of the cutting edges and of the leadingedge of the blade 31 makes it possible to cut the sheath 20 in extremelysatisfactory manner because of the percussion mass effect exerted on thecrease line 20′, which is immediately followed by the top left corner ofthe sheath being cut by the edge 31.1 of the blade and simultaneouslythe right top edge and then the right bottom edge are progressivelyengaged by the cutting edge 31.2. This dual and progressive cuttingtakes place without creasing, with a shear effect that is extremelyfavorable to obtaining a clean cut through the wall of the sheath.

A machine is thus provided for fitting heat-shrink sleeves that isentirely suitable for transferring and fitting sleeves of smalldiameter, e.g. sleeves of diameter lying in the range 5 mm to 20 mm, andenabling this to be done at rates of throughput that can be well inexcess of 200 sleeves per minute. The sleeve is transferred horizontallyin a manner that is under full control and the sleeve is not pinchedexcessively, so unfavorable phenomena of overheating or wear do notarise.

The invention is not limited to the embodiments described above, but onthe contrary covers any variant reproducing the essentialcharacteristics specified above by equivalent means.

What is claimed is:
 1. A machine (1) for fitting sleeves of heat-shrink plastics material on objects (10), the sleeves being taken from a continuous sheath (20) that is rolled up flat, the machine including a shaping mandrel (40) over which the sheath passes to be expanded, sheath drive means (10) using motor-driven wheels which co-operate with an associated portion of the shaping mandrel to engage an open end of the sheath on an object, and cutter means (30) intervening between the shaping mandrel (40) and the object (10) so as to form a sleeve (80) associated with said object, wherein the shaping mandrel (40) is substantially horizontal and comprises two torpedoes (41, 42) in axial alignment interconnected by a flexible wire (43) anchored at both ends (52, 53) in said torpedoes, one of the anchored ends of the flexible wire (43) being releasable so as to enable the length of said flexible wire between said torpedoes to be adjusted, said flexible wire being formed of a steel wire having a diameter of about 1 mm, with an upstream torpedo (41) having an upstream end forming an insertion spatula (44) and a downstream end (45) with a pair of smooth chamfers, and a downstream torpedo (42) presenting an upstream end (46) with a pair of smooth chamfers and a downstream end (47) with a straight edge (51) adjacent to the cutter means (30), each torpedo (41, 42) of said mandrel resting freely in an associated V-support (60), and the sheath drive means (90) comprises, between the two V-supports (60), two adjacent pinch wheels (25, 26) disposed symmetrically on either side of the flexible wire (43) of the shaping mandrel (40) and passing in the vicinity of the chamfered smooth edges of the torpedoes (41, 42), each wheel (25, 26) having a peripheral groove (65, 66) complementary to that of the other wheel (26, 25) so as to form a horizontal axis passage (67) for said flexible wire.
 2. A sleeve-fitting machine according to claim 1, wherein the insertion spatula (44) of the upstream torpedo (41) extends in a plane which is substantially perpendicular to a plane in which the continuous sheath is pinched between the two wheels (25, 26).
 3. A sleeve-fitting machine according to claim 2, wherein the upstream torpedo (41) and/or the downstream torpedo (42) has two plane side facets (58, 59) substantially perpendicular to a plane in which the continuous sheath is pinched between the two wheels (25, 26).
 4. A sleeve-fitting machine according to claim 1, wherein the pairs of smooth chamfers (48, 49) of the upstream and downstream torpedoes (41, 42) are formed by sloping plane facets disposed symmetrically about a midplane containing the flexible wire (43) and tangential to the two pinch wheels (25, 26).
 5. A machine for fitting sleeves according to claim 4, wherein the pair of smooth chamfers (48) of the upstream torpedo (41) is formed by two plane facets sloping at about 30°, and the two pinch wheels (25, 26) pass tangentially over said pair of smooth chamfers (48), while the pair of smooth chamfers (49) of the downstream torpedo (42) is formed by two plane facets that slope at a smaller angle.
 6. A machine for fitting sleeves according to claim 5, wherein the pair of smooth chamfers (48) is defined by two fitted inserts (75), that are preferably interchangeable, having free facets constituting the sloping plane facets that co-operate with the pinch wheels (25, 26).
 7. A machine for fitting sleeves according to claim 1, wherein a longitudinal slot (60.2) is provided in the bottom of the V-grooves of each torpedo support (60).
 8. A machine for fitting sleeves according to claim 1, wherein the cutter means (30) comprise a, blade (31) carried by a rotary arm (32) on a horizontal axis, and said means is positioned in such a manner that its blade (31) is flush with the straight edge (51) of the downstream end (47) of the downstream torpedo (42).
 9. A machine for fitting sleeves according to claim 8, wherein, the cutter blade (31) has two rectilinear cutting edges (31.1, 31.2) that meet at a leading edge (31.3).
 10. A machine for fitting sleeves according to claim 9, wherein the two cutting edges (31.1, 31.2) are substantially perpendicular and arranged in such a manner that the leading edge (31.3) meets the top (20′) of the sheath in the vicinity of a crease therein that results from said sheath passing over the insertion spatula (44) or between the two pinch wheels (25, 26).
 11. A machine for fitting sleeves according to claim 1, wherein the two pinch wheels (25, 26) are peripherally coated in elastomer, and come into contact with each other on either side of their peripheral grooves (65, 66) which are trapezoidally shaped and present two facets (68, 69) sloping symmetrically about their midplane (P), forming a V that opens at an angle of about 60°.
 12. A machine for fitting sleeves according to claim 11, wherein the two pinch wheels (25, 26) are chamfered on their outer edges (70, 71).
 13. A machine for fitting sleeves according to claim 1, wherein the two pinch wheels (25, 26) are mounted on a carrying structure (23) capable of pivoting, preferably about a vertical axis (19), so as to enable the drive means (90) as a whole to be offset laterally. 